1. Field of the Invention
The present invention relates to a manufacturing method for thin film semiconductor device, a manufacturing method for a thin film semiconductor array substrate, a method of forming a crystalline silicon thin film, and an apparatus for forming a crystalline silicon thin film.
2. Description of the Related Art
In an active-matrix driven display device such as an organic electro luminescence (EL) display apparatus or a liquid crystal display, thin film semiconductor devices known as thin film transistors (TFT) are used.
In this type of display apparatus, an array of the thin film transistors configures a thin film transistor array device. In each pixel, a thin film transistor for driving the pixel (driving transistor) and a thin film transistor used for selecting the pixel (switching transistor) are formed.
In particular, in the light-emitting organic EL display apparatus having organic EL devices, different capabilities are required for driving transistors and switching transistors. More specifically, good turn-on characteristics are required for the driving transistors in order to improve the driving capability of the organic EL devices, and good turn-off characteristics are required for the switching transistors.
A thin film transistor includes a gate electrode, a semiconductor layer (channel layer), a source electrode, and a drain electrode that are formed on the substrate, and a silicon thin film is generally used as the channel layer. The silicon thin films are roughly classified into non-crystalline silicon thin films (amorphous silicon film) and crystalline silicon thin films.
A thin film transistor with a crystalline silicon thin film as the channel layer has larger carrier mobility and better turn-on characteristics compared to a thin film transistor having the non-crystalline silicon thin film as the channel layer. Accordingly, there is a known technology using the crystalline silicon thin film as the channel layer of the driving transistor, and Patent Literature 1: Japanese Unexamined Patent Application Publication No. H07-235490 discloses a technology for forming the crystalline silicon thin film, for example.
The conventional method of forming the crystalline silicon thin film disclosed in Patent Literature 1, is a method for poly-crystallizing the amorphous silicon film formed on the substrate by setting the amorphous silicon film to a predetermined temperature, and irradiating the amorphous silicon film with laser at a predetermined laser energy density.